Drainage containers have been known for use in various medical procedures. For many years, the standard apparatus for performing the evacuation of the pleural cavity was a collection system known as the "3-bottle set-up" which includes a collection bottle, a water seal bottle and a suction control bottle. A catheter runs from the patient's pleural cavity to the collection bottle, and the suction bottle is connected by a tube to a suction source. The three bottles are connected in series by various tubes to apply suction to the pleural cavity to withdraw fluid and air and thereafter discharge the same into the collection bottle. Gases entering the collection bottle bubble through water in the water seal bottle. The water in the water seal also usually prevents the back flow of air into the chest cavity.
The 3-bottle set-up lost favor with the introduction of an underwater seal collection system sold under the name "Pleur-evac".RTM. in 1966 by Deknatel Inc. (a more detailed description of the need for and the proper use of chest collection devices is presented in the Deknatel Inc. Pleur-evac.RTM. publication entitled "Physiology of the Chest and Thoracic Catheters: Chest Drainage Systems No. 1 of a series from Deknatel" (1985) which is incorporated herein in its entirety). U.S. Pat. Nos. 3,363,626; 3,363,627; 3,559,647; 3,683,913; 3,782,497; 4,258,824; and U.S. Pat. No. Re. 29,877 are directed to various aspects of the Pleur-evac.RTM. system which over the years has provided improvements that eliminated various shortcomings of the 3-bottle set-up. These improvements have included the elimination of variations in the 3-bottle set-up that existed between different manufacturers, hospitals and hospital laboratories. Such variations include bottle size, tube length and diameter, stopper material and the like.
Among the features of the Pleur-evac.RTM. system which provide its improved performance are employment of 3-bottle techniques in a single, pre-formed, self-contained unit. The desired values of suction are generally established by the levels of water in the suction control bottle and the water seal bottle. These levels are filled according to specified values prior to the application of the system to the patient. A special valve referred to as the "High Negativity Valve" is included which is employed when the patient's negativity becomes sufficient to threaten loss of the water seal. Also, a "Positive Pressure Release Valve" in the large arm of the water seal chamber works to prevent a tension pneumothorax when pressure in the large arm of the water seal exceeds a prescribed value because of suction malfunction, accidental clamping or occlusion of the suction tube. The Pleur-evac.RTM. system is disposable and helps in the battle to control cross-contamination.
Despite the advantages of the Pleur-evac.RTM. system over the 3-bottle set-up and the general acceptance of the device in the medical community, there remains a continuing need to improve the convenience and performance of chest collection systems and to render such systems compact.
Also, in a number of surgical procedures referred to in the art as cardiopulmonary bypass operations, it is necessary to interrupt and suspend the normal functioning of the patients's heart and lungs and to temporarily replace the function of these organs with artificial blood handling and treating units in a life-sustaining extracorporeal blood flow circuit. In these procedures, the main body of the patient's blood, which is called the venous return stream, is typically withdrawn from the patient through a venous cannula inserted into the right atrium, collected in a venous reservoir, and then passed through a blood pump (artificial heart), blood oxygenator (artificial) lung) and arterial blood filter before being returned to the patient through an aortic cannula inserted into the aorta distal to the aorta arch. In conventional practice, the venous reservoir is a flexible transparent bag with a blood outlet in the bottom. Additionally, in typical practice, patient's blood from the surgical field, which is called cardiotomy blood, is gathered in one or more cardiac vacuum suckers and defoamed, filtered and collected in a cardiotomy reservoir and filter device. The treated cardiotomy blood is then conducted to the venous reservoir, where it is combined with the venous return blood.
In addition, blood supplied to a patient must usually be purified by filtration to avoid jeopardizing the patient. The blood may be obtained from the patient during various surgical procedures when it is advantageous to store excess blood outside the body to facilitate the surgical procedures, or in blood conservation by scavenging the blood from the wound. Such blood is usually collected in a cardiotomy reservoir and purified there by passage through a filter unit within the reservoir. The blood passing through the cardiotomy reservoir must not only be purified of undesirable particulate matter such as surgical debris, but must also be freed of entrained air bubbles before being returned to the patient.
It is known to provide in a cardiotomy reservoir a filter unit including means for screening out particulate matter, and means for defoaming the blood to remove the air trapped therein. Examples of such known devices include those disclosed in U.S. Pat. Nos. 3,507,395 and 3,768,653. The former discloses a cardiotomy reservoir comprising a chamber containing a plate surrounded by a fibrous filter element contained in a nylon bag. The plate first spreads the incoming blood to remove the air bubbles therefrom which are vented, or drawn by vacuum, from the chamber, and the filter removes solid particles from the blood as it passes therethrough before leaving the chamber. U.S. Pat. No. 3,768,653 discloses a cardiotomy reservoir comprising a tubular chamber having a tangential inlet for the blood which is directed onto a filter across one end of the chamber which also contains a conical air filter.
Many other filtration systems are known for filtering blood and many use multiple layer elements to remove unwanted materials from the blood as it passes through. the layers. U.S. Pat. Nos. 3,765,536 and 3,765,537 disclose a multiple layer blood filter elements including one comprising a first layer of coarse polypropylene netting, a second downstream layer of open-mesh polyester, a third spacer layer of polypropylene netting, a fourth microporous layer and a fifth polypropylene netting spacer layer.
I have invented an improved reservoir for use alone or with a collection device which provides additional improvements to presently available containers.